That is wrong. You do not need any points into Sneak to snatch the prison key. All you need to do is to get close to it while keeping your body outside the sight cone, and you can still take the key off of the stool without being seen even though it is inside the sight cone.
Yeah. I just tried that the other day: first time I got caught; thanks to the handy autosave immediately beforehand I had another go, more carefully manoeuvring my totally unsneaky character into place and swiped it without incident.
